The two forms of subterranean termites that are of concern for pest control are subterranean termites, which typically nest in the ground and usually maintain some sort of ground connection, and drywood termites, which start as a pair in a piece of wood and do not have a ground connection. Subterranean termites are the most damaging termites and usually enter buildings from the surrounding soil. There have been several methods of subterranean termite control. For example, the most common method of subterranean termite control requires soil underlying a structure to be treated with a termiticide barrier (usually hundreds of gallons of termiticide per house) to prevent termites from entering the structure from the ground. From 1950 to 1988 the chlorinated hydrocarbons were the main method of barrier treatment to control subterranean termites; however, environmental concerns with those chemical treatments resulted in the loss of chlorinated hydrocarbons that lasted up to 35 years in the soil. Chemicals that replaced the chlorinated hydrocarbons for barrier treatment have had a high rate of failure resulting in extensive termite damage to structures. The problems with the barrier treatments are compounded since builders have often been known to dump substantial amounts of edible building materials, such as wood and cardboard into the underlying soil that can serve as Guidelines into the structures and provide a substantial food source, increasing the probability of termite infestation in the structure. Several systems have been proposed to enhance the underground delivery of toxic insecticides beneath structures. See for example, U.S. Pat. Nos. 3,940,875 and 4,043,073 to Basile; and U.S. Pat. No. 4,625,474 to Peacock. However, these systems are only concerned with trying to refresh the initial termiticide barrier by having the termites chew through a container with the toxicant (Basile) or by installing a piping system during construction so that additional termiticide can be pumped under a slab at intervals after construction. Furthermore, the Basile patent utilized a toxicant (dieldrin) that has been banned by the EPA for termite treatment, and the pipe system often got clogged after installation making it not usable.
Other well-known subterranean termite treatments include bait techniques, which require termites to forage into a monitor that contains a non-toxic food source. Once termites infest the non-toxic food source, a food source laced with a toxicant (toxic bait) is replaced into the monitor. Termites continue to recruit to the monitor and feed on the toxic bait. Consumption and trophallaxis (feeding other termites) of the toxic bait causes many termites to die. See for example, U.S. Pat. No. 5,329,726 to Thorne et al.; U.S. Pat. No. 5,899,018 to Gordon et al.; and U.S. Pat. No. 5,950,356 to Nimocks. However, these techniques generally require that the termites consume the toxic bait. Termites refuse to consume most toxicants; therefore this technique is useful for only 2-3 toxicants currently known in the world. Termites also refuse to consume bait food sources that are contaminated with molds or are too wet. These bait techniques do not use a non-edible foraging matrix (described in our invention), such as soil, to cause the termites to tunnel therethrough and carry the particles treated with toxicant to the galleries and living spaces of the colony; thus contaminating them. Most toxicants applied to non-edible foraging matrix, except the repellent pyrethroids, will be picked up and carried by termites to other areas of their tunnel system.
Other systems have been proposed but still fail to overcome the problems with the methods and applications described for the cited patents above. See for example, U.S. Pat. No. 3,972,993 to Kobayashi et al. requires a membrane treated with a substance attractive to termites (due to the termite's innate searching and feeding behavior, termites are not attracted to food from a distance when allowed to forage without interference) so that when the termites chew through the membrane a toxic surface is contacted; U.S. Pat. No. 5,501,033 to Wefler delivers a liquid toxic food source for social insects like yellow jackets and has very little use for termites; U.S. Pat. No. 5,609,879 to Myles requires the laborious harvesting of termites from the ground, sponging on an insecticidal epoxy, and returning them to the soil; U.S. Pat. No. 5,778,596 to Henderson et al. is a device for delivering toxic food for termites to consume; U.S. Pat. No. 5,921,018 to Hirose provides foraging guidelines for termites to follow so they enter a device that captures and kills them.
There are additional problems with prior art treatments that use repellent liquids, non-repellent liquids, and baits. When using repellent liquids, the liquid barriers need to be applied in a perfectly continuous fashion. If gaps in the treatment exist, especially with repellent termiticides, such as those belonging to the pyrethroid class, the termites will forage and find the gaps in the treatment, increasing the probability of infesting the structure.
In non-repellent liquid treatments, the termites are not able to detect that they are in a treated area; hence the classification "non-repellent," and they die. A major drawback is that liquid termiticides in this class are new and there are questions about how long they will last in the soil, especially when exposed to sun and weather. The present invention protects the foraging matrix from sun and weather to prolong its usability, and the foraging matrix can be replaced as necessary to recharge the system. The application of liquid termiticide barriers requires several hundred gallons of insecticide that are pumped under houses, sometimes resulting in contamination of the house interior and water supply wells. Most homeowners want applications that are less intrusive and disruptive.
Baits require a food source that is palatable to termites. Selecting the appropriate food source can be difficult. Wood is very inconsistent in composition, so manufacturers don't like to use it for use with toxicants. Paper food sources, if not packed tightly enough, will be emptied by termites and not deliver enough toxicant to kill large numbers of termites. Most cellulose material will rot when placed in the soil. Once the food goes bad, termites will not feed, rendering the bait ineffective. The subject invention uses a non-edible foraging matrix treated with a slow-acting non-repellent toxicant. Termites put the particles of the treated matrix into their mouths when they tunnel through it, and many toxicants will work because they do not need to consume it and feed it to others. The particles are returned to the colony and incorporated into their tunnels. Termites that contact the particles die several days after the toxicant on the matrix particles are contacted. The behavior of the termites moves the treated foraging matrix from the exit and entrance opening of the device's chamber to contaminate their colony and tunnels.